Preparation of acrylic acid esters



Unite States Patent C PREPARATION OF ACRYLIC ACID ESTERS Jesse Dunn andWilliam R. Proops, Charleston, W. Va., assignors to Union CarbideCorporation, a corporation of New York No Drawing. Filed Apr. 1, 1958,Ser. No. 725,483

9 Claims. (Cl. 260-486) This invention rel-ates to the production ofacrylic acid esters. More particularly it is concerned With newcatalysts for carrying out the interaction of acetylene, carbon monoxideand an alcohol to produce acrylic acid esters.

It is well known that acrylic acid and its esters can be produced by thereaction of acetylene and carbon monoxide with compounds having areplaceable hydrogen,

such as water, alcohols, carboxylic acids, ammonia and amines, in thepresence of a metal carbonyl, or other catalyst, for example, thecomplex triphenyl phosphinenickel halide compounds, or the complexnickel halidequaternary ammonium compounds.

It has now been found that the complex combinations obtained by theadmixture of a nickel halide with a disulfide of an organicsulfur-phosphorus-containing acid are Very efiicient catalysts for theproduction of acrylic acid esters from acetylene, carbon monoxide and analcohol at milder conditions of temperature and pressure than heretoforeemployed. 7

The catalyst complexes suitable for use as catalysts in this inventionare prepared by admixing a nickel halide, such as nickel bromide, nickelchloride, nickel fluoride and nickel iodide, with a disulfide of anorganic sulfurphosphorus-containing acid. In preparing the complex it isimmaterial which component is added to the other. While the complex isan active catalyst, its exact chemical composition is not yet known.

The disulfides of the organic sulfur-phosphorus-conraining acids usefulin preparing the catalyst complexes of this invention contain thepent'avalent phosphorus atom in what we call the bis-(phosphorthio)disulfide radical as represented by the general formula:

The suitable disulfides are the disulfides of the organicdithiophosphoric acid compounds, which can be represented by the generalformula:

or the disulfides of the organic dithiophosphonic acid compounds, whichcan be represented by the general fonnula:

R Z i or the disulfides of the organic dithiophosphinic acid compounds,which can be represented by the general formula:

wherein R and R when taken singly can represent an unsubstituted orsubstituted alkyl radical containing up to about 22 carbon atoms ormore, such as methyl,ethyl,

propyl, butyl, chloroethyl, chloropropyl, methoxyethyl,methoxyethoxyethyl, Z-ethylhexyl, benzyl, phenethyl, and the like, anunsubstituted or substituted aryl radical such as phenyl, naphthyl,tolyl, xylyl, chlorophenyl, dichlorophenyl, nitrophenyl, nitrotolyl, andthe like, a trihydrocarbylsilanyl radical, for example, a trialkylortriarylsilanyl radical such as tn'ethylsilanyl or triphenylsilanyl andthe like; and Z represents an oxygen atom or an amido (NH or NR)radical; and when taken together RZ and RZ can represent a cyclic dioxanucleus or a substituted cyclic dioxa nucleus. By the term cyclic dioxanucleus is meant a cyclic group as represented by the following formula:

(7-0 wherein the two oxygen atoms (Z) are connected to the phosphorusatom of the group and wherein the carbon atoms of the dioxa nucleus havetheir other valences satisfied by hydrogen atoms or other radicals.Hereinafter the terms alkyl radicals and aryl radicals Will be used torepresent both the unsub stituted and substituted radicals.

Illustrative of the disulfides of the organic dithiophosphoric acidcompounds which are suitable for use in this invention there may bementioned the disulfides of.0,0- dicresyldithiophosphoric acid, 0,0 di(2,4 dichlorophenyD-dithioplrosphoric acid, 0,0'-di-(4-nitrophenyl)-dithiophosphoric acid, 0,0-diethyldithiophosphoric acid,

0,0-di-(2-ethylhexyl)-dithiophosphoric acid, 0,0-di-(2- methoxyethyl)dithiophosphoric acid, 0,0 di [2 (2-rnethoxyethoxy)ethyl]-dithiophosphoric acid, 0,0-di-(2-ethylbutyl)-dithiophosphoric acid,0,0-di-(triethylsilanyl)-dithiophosphoric acid,0,0-di-triphenylsilanyl)- dithiophosphoric acid,N,N'-dipropyldiamidodithiophosphoric acid,N-methyl-N'-propyldian'iido-dithi-ophosphoric acid,N,N-diphenyldiamidodithiophosphoric acid, 5,5-diethyl-Z-mercapto-Z-thiono-l,3,2-dioxaphosphoiinane, 5- ethyl 2mercapto 4 propyl 2 thiono 1,3,2 dioxaphosphorinane,2,4-dioxa-P-mercapto-S-methyl-P-thiono- 3-phosphabicyclo [4.4.0] decane,and the like.

Among the disulfides of the organic dithiophosphonic acid compoundssuitable for use in this invention are the disulfides of O-cresylethanedithiophosphonic acid, O-ethyl propanedithiophosphonic acid,O-phenyl benzenedithiophosphonic acid, 'O-(2-ethylhexyl)toluenedithiophos- I the nickel halide thereto, or the reverse order ofaddition can be used.

The starting alcohols are preferably the aliphatic monoa hydroxysaturated alcohols having up to about 22 carbon atoms, and preferablyfrom about 1 to about lZ earbon atoms in the molecule. Illustrativealcohols are ethanol, pentanol, 2-ethylhexanol, dodecanol,3-ethyl-2-pentanol, ethylene glycol monomethyl ether, ethylene glycolmonoethyl ether, and the like.

The acrylic acid esters are produced by the interaction of acetylenewith carbon monoxide and an alcohol at elevated temperature and underincreased pressure in the presence of a catalytic amount of the complexcombina tion produced with a nickel halide and a disulfide of an organicdithiophosphoric acid.

The reaction is successfully carried out with our catalyst complex attemperatures of from about 90 C. to about 250 C. or higher. Temperaturesof from about 100 C. to about 200 C. are preferred. The reaction can beexpedited by the use of slight pressures; and we prefer to work atpressures exceeding about 100 p.s.i.g., with pressures of from about 400p.s.i.g. to about 500 psig. most preferred. Higher pressures can, ofcourse, be used with proper precautions.

The mole ratio of nickel halide to disulfide of the organicsulfur-phosphorus-containing acid can be varied over wide limits, anddoes not appear to be critical; nevertheless, we prefer to employequimolar amounts of each component. The amount of catalyst complexcharged to the reaction mixture is not critical, and can be varied overa wide range so long as a catalytic amount is present. When based on thealcohol charged, it has been found that a catalyst complex containingabout 0.0622 mole each of the nickel halide and the disulfide of theorganic sulfur-phosphorus-containing acid per 16 moles of alcohol yieldsthe highest conversions from an economical viewpoint. Higherconcentrations of catalyst would give a faster reaction, but wouldrequire a greater expense in catalyst cost; while lower concentrationswould be more economical as far as catalyst cost is concerned, but theproductivity would suffer.

The reaction can be carried out in a batch-wise or in a continuousmanner by methods which are known to the 7 art. The acetylene and carbonmonoxide can be added separately, or for reasons of safety, as a mixtureof gases, which mixture can be widely varied in composition.

The following examples further serve to illustrate this invention. Partsare by weight unless otherwise specified.

Example 1 A three-liter stainless steel rocking autoclave was chargedwith 740 g. of ethanol, 38.5 g. of the disulfide of0,0'-dicresyldithiophosphoric acid and 13.6 g. of nickel bromide, sealedand purged with carbon monoxide and then with a 1: 1 mixture, by volume,of acetylene and carbon monoxide. The autoclave was rocked and thepressure increased to 40 p.s.i.g. by the further addition of theacetylene-carbon monoxide mixture. The gas addition was halted and theautoclave was heated to 100 C., at which time the pressure was increasedp.s.i.g. by the addition of acetylene. The total pressure wasthen'increased to 300 p.s.i.g. with the acetylene-carbon monoxidemixture, and heating continued to a temperature of 150 C. At this pointthe pressure was increased to 450 p.s.i.g., and maintained between 400p.s.i.g. to 450 p.s.i.g. by the periodic addition of theacetylene-carbon monoxide mixture for 3.8 hours. During this period thetemperature was maintained between 150 C. to 170 C. The reaction wasstopped by cooling the autoclave with air, and then releasing thepressure. The reaction mixture was filtered to remove solid materials,and the filtrate was distilled to separate the monomeric ethyl acrylate,most'of which distilled as the ethyl acrylate-ethanol azeotrope, fromthe higher boilingacrylateesters and polymer-containing residue." The.

4 total yield of monomeric ethyl acrylate obtained was 410 g.

In similar manner one produces the propyl or butyl esters of acrylicacid by substituting the appropriate alcohol for ethanol.

Example 2 In the manner described in Example 1, 740 g. of ethanol wastreated with acetylene and carbon monoxide at 143 C. to 154 C. over a 5hour period in the presence of a complex combination of 13.6 g. ofnickel bromide and 44 g. of the disulfide ofdi-(2-ethylhexyl)-dithiophosas catalyst. The yield of monomeric ethylacrylate was 445 g.

Example 4 In the manner described in Example 1, 740 grams of ethanol wastreated with acetylene and carbon monoxde at C. to C. over a 5 hourperiod in the presence of a complex combination of 13.6 g. of nickelbromide and 31 g. of the disulfide of diphenyl dithiophos phinic acid Coa .Jr

as catalyst. The yield of monomeric ethyl acrylate was 340 g.

What is claimed is:

1. In the manufacture of an acrylic acid ester by the inter-action ofacetylene with carbon monoxide and an alcohol at elevated temperatureand under increased pressure, the improvement which comprises carryingout the reaction in the presence of a catalyst complex combination of anickel halide and a disulfide of an organic sulfur-phosphorus-containingacid compound having pentavalent phosphorus in the bis-(phosphorthio)disulfide radical thereof, said bis-(phosphorthio) disulfide radicalhaving the formula:

in which all of the free valences bonds thereof are satisfied by membersselected from the group consisting of R, R, RZ and R'Z groups, wherein Rand R singly are members selected from the group consisting of alkylradicals containing up to about 22 carbon atoms, aryl radicals selectedfrom the group consisting of a phenyl and naphthyl radical, andtrihydrocarbylsilanyl radicals; Z represents a member selected from thegroup consisting of an oxygen atom and an amide radical; and when takentogether RZ and R'Z attached to the same phosphorus atom represent acyclic dioxa nucleus.

2. In the manufacture of an acrylic acid ester by the inter-action ofacetylene with carbon monoxide and an alcohol at elevated temperatureand under increased pressure, the improvement which comprises carryingout the reaction in the presence of a catalyst complex combination of anickel halide and a disulfide of an organic dithiophosphoric acidselected from the group represented by the general formula:

wherein R and R' singly are members selected from the group consistingof alkyl radicals containing up to about 22 carbon atoms, aryl radicalsselected from the group consisting of a phenyl radical and naphthylradical and trihydrocarbylsilanyl radicals; Z represents a memberselected from the group consisting of an oxygen atom and an amidoradical; and when taken together RZ and R'Z represent a cyclic dioxanucleus. 7

3. In the manufacture of an acrylic acid ester by the inter-action ofacetylene with carbon monoxide and an alcohol at elevated temperatureand under increased pressure, the improvement which comprises carryingout the reaction in the presence of a catalyst complex combination of anickel halide and a disulfide of an organic dithiophosphinic acidselected from the group represented by the general formula:

wherein R and R represent members selected from the group consisting ofalkyl radicals containing up to about 22 carbon atoms, aryl radicalsselected from the group consisting of a phenyl radical and naphthylradical and trihydrocarbylsilanyl radicals.

4. In the manufacture of an acrylic acid ester by heating at atemperature between about 90 C. and about 250 C. and under a pressureexceeding 100 p.s.i.g. an aliphatic monohydroxy saturated alcohol havingfrom 1 to about 12 carbon atoms with carbon monoxide and acetylene, theimprovement which comprises carrying out the reaction in the presence ofa catalyst complex combination of a nickel halide and a disulfide of anorganic dithiophosphoric acid selected from the group represented by thegeneral formula:

wherein R and R singly are members selected from the group consisting ofalkyl radicals containing up to about 22 carbon atoms, aryl radicalsselected from the group consisting of a phenyl radical and naphthylradical and trihydrocarbylsilanyl radicals; Z represents a memberselected from the group consisting of an oxygen atom and an amidoradical; and when taken together RZ and R'Z represent a cyclic dioxanucleus.

5. In the manufacture of an acrylic acid ester by heating at atemperature between about 90 C. and about 250 C. and under a pressureexceeding 100 p.s.i.g. an aliphatic monohydroxy saturated alcohol havingfrom 1 to about 12 carbon atoms with carbon monoxide and acetylene, theimprovement which comprises carrying out the reaction in the presence ofa catalyst complex combination of a nickel halide and a disulfide of anorganic dithiophosphinic acid selected from the group represented by thegeneral formula:

7. In the manufacture of an acrylic acid ester by the inter-action ofacetylene with carbon monoxide and an alcohol at elevated temperatureand under increased pressure, the improvement which comprises carryingout the reaction in the presence of a catalyst complex combination of anickel halide and 8. In the manufacture of an acrylic acid ester by theinter-action of acetylene with carbon monoxide and an alcohol atelevated temperature and under increased pressure, the improvement whichcomprises carrying out the reaction in the presence of a catalystcomplex combination of a nickel halide and /CHr-O\fi |:(0=H5):C 1=-sCHr-Q II 9. In the manufacture of an acrylic acid ester by theinter-action of acetylene with carbon monoxide and an alcohol atelevated temperature and under increased pressure, the improvement whichcomprises carrying out the reaction in the presence of a catalystcomplex combination of a nickel halide and References Cited in the fileof this patent UNITED STATES PATENTS 2,806,040 Reppe et al. Sept. 10,1957 FOREIGN PATENTS 805,641 Germany May 25, 1951

1. IN THE MANUFACTURE OF AN ACRYLIC ACID ESTER BY THE INTER-ACTION OFACETYLENE WITH CARBON MONOXIDE AND AN ALCOHOL AT ELEVATED TEMPERATUREAND UNDER INCREASED PRESSURE, THE IMPROVEMENT WHICH COMPRISES CARRYINGOUT THE REACTION IN THE PRESENCE OF A CATALYST COMPLEX COMBINATION OF ANICKEL HALIDE AND A DISULFIDE OF AN ORGANIC SULFUR-PHOSPHORUS-CONTAININGACID COMPOUND HAVING PENTAVALENT PHOSPHORUS IN THE BIS-(PHOSPHORTHIO)DISULFIDE RADICAL THEREOF, SAID BIS-(PHOSPHORTHIO) DISULFIDE RADICALHAVING THE FORMULA: